1. Field of the Invention
The present invention relates to a snowplow vehicle having an engine equipped with a silencer or muffler for reducing the noise level when exhaust gases from the engine pass through the muffler.
2. Background Information
Rotary snowplow machines or vehicles equipped with a snowplow unit disposed at a front end of the vehicle body are known as disclosed, for example, in Japanese Utility Model Laid-open Publication (JP-UM-A) No. 64-5919. The snowplow unit of the disclosed snowplow vehicle comprises a snow worm or auger that delivers snow, a fan blower that throws the delivered snow upwardly, and a guide duct or shooter that guides the thrown snow into a selected direction. The snowplow vehicle has an engine mounted on an upper part of the vehicle body, left and right propelling crawler units disposed on lower left and right sides, respectively, of the vehicle body, and left and right handlebars extending from a rear part of the vehicle body in a backward direction of the vehicle. Thus, the disclosed snowplow vehicle is a self-propelled walk-behind vehicle that is maneuvered by a human operator walking behind the snowplow vehicle while grasping handgrips of the handlebars.
The self-propelled walk-behind snowplow vehicle includes an exhaust system having a muffler disposed on a left side of the engine above the left crawler belt, and a tail pipe extending from the muffler in a lateral outward direction of the snowplow vehicle. The muffler thus disposed is located at a relatively high position. To the operator who is standing near the muffler during snowplow operation, exhaust sound from the muffler is felt loud and unpleasant. Furthermore, the muffler located at a relatively high position may obstruct field of vision of the operator when the operator is looking ahead of the snow auger. A further problem is that when the snowplow vehicle is traveling alongside a snow wall, a stream of exhaust gases emitted from the tail pipe in a lateral outward direction is partly reflected from the snow wall in a backward direction of the snowplow vehicle and thereafter comes into the face of the operator. At the same time, the stream of exhaust gases may splash snow flakes from the snow wall, which will shower onto a body of the operator as the snowplow vehicle travels forward.
Another example of the conventional rotary snowplow vehicles is disclosed in Japanese Patent Publication (JP-B) No. 60-38491. The disclosed snowplow vehicle includes an engine mounted on a body of the vehicle, a top cover disposed on the vehicle body so as to conceal the engine with a space defined between a rear end of the vehicle body and a rear end the top cover, an exhaust pipe extending from the engine downward through the space between the vehicle body and the top cover, and a muffler connected to a lower end of the exhaust pipe.
The muffler thus arranged at a lower position of the snowplow vehicle does not obstruct forward view of the operator. However, since the muffler is disposed at the rear end of the vehicle body, exhaust sound from the muffler is still loud and gives unpleasant feel to the operator. Another drawback associated with the prior arrangement is that the space defined between the rear end of the vehicle body and the rear end of the top cover allows entry of radiant heat from the muffler, which will lower the engine cooling efficiency.